Tag: epfl

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Photonic-plasmonic linear and non-linear coupling

Glass is transparent. Metals are shiny. A piece of wood is opaque. Each material has a different relationship with light. Some materials let light go through; others reflect back; others absorb it. This is true also at the nanoscale. In addition, optical properties at the nanoscale are even more interesting. Imagine if your gold ring would change its color if you break it in half, or if you change its size anyhow. In fact, this is what happens for nano-sized metals and semiconductors. In particular, metals can act as an antenna for light. Gold nanopads have the ability to redirect light in specific directions and locations. Semiconductors change their response to light depending on its size and shape. What about coupling the two systems?

Within this research field, I investigated the optical properties of new semiconductor architectures (V-shaped membranes). Fabrication of these structures is very challenging and we did it in collaboration with Prof. Fontcuberta group at EPFL. I studied the their optical properties, analyzing the change in the scattering spectra as the size is changed. I used second harmonic generation to probe the non-linear properties of such nanostructures, finding very interesting correlation between structural properties and optical behavior.

Second harmonic excitation spectroscopy is a very powerful too to investigate material properties. I used it to characterize substoichiometric silicon nitride thin films, to elucidate size-dependent effects on gold nanoparticles, and to obtain polarization-controlled multispectral nanofocusing of metal nanoantennas.

Moreover, I investigated the coupling between photonic and plasmonic properties. In collaboration with EPFL, we designed gold nanoantenna arrays coupled with gallium arsenide nanowires. By using second harmonic excitation spectroscopy, we elucidated all the coupling effects in these systems and we showed that new modes emerge at expenses of the expected structural resonances.

These projects have been funded by the Air Force Office of Scientific Research, and performed during my experience at Boston University.

Publication output

Conference proceedings

  • Integration of metallic nanostructures on nanowires for modification of their optical properties
    A. Casadei, E. Alarcon-Llado, E. F. Pecora, J. Trevino, C. Forestiere, D. Ruffer, E. Russo-Averchi, F. Matteini, G. Tutuncuoglu, M. Heiss, L. Dal Negro, A. Fontcuberta i Morral
    Frontiers in Nanophotonics, CSF Conference 2015
  • Second harmonic excitation spectroscopy in studies of Fano-type coupling in plasmonic arrays
    G. F. Walsh, J. Tervino, E. F. Pecora, L. Dal Negro
    SPIE Optics + Photonics 2015
  • Engineering light coupling in single nanowire with metal nano-antennas
    A. Casadei, J. Trevino, E. F. Pecora, E. Alarcò- Lladò, D. Ruffer, E. Russo-Averchi, G. Tutuncuoglu, F. Matteini, C. Forestiere, L. Dal Negro, A. Fontcuberta i Morral
    International Conference on One dimensional Nanomaterials ICON 2013
  • Second-harmonic generation from plasmonic nanoantennas and arrays
    A. Capretti, C. Forestiere, E. F. Pecora, G. Walsh, J. Trevino, S. Minissale, L. Dal Negro, G. Miano
    The International Conference on Surface Plasmon Photonics SPP6
  • Second-harmonic generation in substoichiometric silicon nitride layers
    E. F. Pecora, A. Capretti, G. Miano, L. Dal Negro
    Bulletin of the American Physical Society, vol. 58, V1.00119
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Photonic-Plasmonic Coupling of GaAs Single Nanowires to Optical Nanoantennas

We successfully demonstrate the plasmonic coupling between metal nanoantennas and individual GaAs nanowires (NWs). In particular, by using dark-field scattering and second harmonic excitation spectroscopy in partnership with analytical and full-vector FDTD modeling, we demonstrate controlled electromagnetic coupling between individual NWs and plasmonic nanoantennas with gap sizes varied between 90 and 500 nm. The significant electric field enhancement values (up to 20×) achieved inside the NW-nanoantennas gap regions allowed us to tailor the nonlinear optical response of NWs by engineering the plasmonic near-field coupling regime. These findings represent an initial step toward the development of coupled metal–semiconductor resonant nanostructures for the realization of next generation solar cells, detectors, and nonlinear optical devices with reduced footprints and energy consumption.

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Vertical III-V V-shaped membranes epitaxially grown on a patterned Si[001] substrate and their enhanced light scattering

We report on a new form of III–V compound semiconductor nanostructures growing epitaxially as vertical V-shaped nanomembranes on Si(001) and study their light-scattering properties. Precise position control of the InAs nanostructures in regular arrays is demonstrated by bottom-up synthesis using molecular beam epitaxy in nanoscale apertures on a SiO2 mask. The InAs V-shaped nanomembranes are found to originate from the two opposite facets of a rectangular pyramidal island nucleus and extend along two opposite 111 B directions, forming flat {110} walls. Dark-field scattering experiments, in combination with light-scattering theory, show the presence of distinctive shape-dependent optical resonances significantly enhancing the local intensity of incident electromagnetic fields over tunable spectral regions. These new nanostructures could have interesting potential in nanosensors, infrared light emitters, and nonlinear optical elements.

For more info:

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Boston University

PostDoctoral Associate at the Photonics Center of Boston University from 2011, March to 2013, August.

Research projects

Publication output

Conference proceedings

  • Integration of metallic nanostructures on nanowires for modification of their optical properties
    A. Casadei, E. Alarcon-Llado, E. F. Pecora, J. Trevino, C. Forestiere, D. Ruffer, E. Russo-Averchi, F. Matteini, G. Tutuncuoglu, M. Heiss, L. Dal Negro, A. Fontcuberta i Morral
    Frontiers in Nanophotonics, CSF Conference 2015
  • Second harmonic excitation spectroscopy in studies of Fano-type coupling in plasmonic arrays
    G. F. Walsh, J. Tervino, E. F. Pecora, L. Dal Negro
    SPIE Optics + Photonics 2015
  • Engineering light coupling in single nanowire with metal nano-antennas
    A. Casadei, J. Trevino, E. F. Pecora, E. Alarcò- Lladò, D. Ruffer, E. Russo-Averchi, G. Tutuncuoglu, F. Matteini, C. Forestiere, L. Dal Negro, A. Fontcuberta i Morral
    International Conference on One dimensional Nanomaterials ICON 2013
  • Second-harmonic generation from plasmonic nanoantennas and arrays
    A. Capretti, C. Forestiere, E. F. Pecora, G. Walsh, J. Trevino, S. Minissale, L. Dal Negro, G. Miano
    The International Conference on Surface Plasmon Photonics SPP6
  • Sub-250nm room temperature optical gain from AlGaN materials with strong compositional fluctuations
    E. F. Pecora, W. Zhang, H. Sun, A. Yu. Nikiforov, J. Yin, R. Paiella, T. D. Moustakas, L. Dal Negro
    Bulletin of the American Physical Society, vol. 58, V1.00111
  • Second-harmonic generation in substoichiometric silicon nitride layers
    E. F. Pecora, A. Capretti, G. Miano, L. Dal Negro
    Bulletin of the American Physical Society, vol. 58, V1.00119
  • Rare-earth doped Si-rich ZnO for multiband near-infrared light emitting devices
    E. F. Pecora, T. I. Murphy, L. Dal Negro
    Bulletin of the American Physical Society, vol. 58, C23.00004
  • Nanopatterning of optically-active silicon nanowires
    E. F. Pecora, N. Lawrence, P. Gregg, J. Trevino, P. Artoni, A. Irrera, F. Priolo, L. Dal Negro
    Frontiers in Optics (FiO) – Novel Silicon Waveguides and Nanophotonics (FM4E)
  • Sub-250nm room temperature optical gain from AlGaN/AlN multiple quantum wells structures
    E. F. Pecora, W. Zhang, L. Zhou, D. J. Smith, J. Yin, R. Paiella, L. Dal Negro, T. D. Moustakas
    CLEO: Science and Innovations, CTh3D, CTh3D.5
  • Sub-250nm room-temperature optical gain from AlGaN/AlN multiple quantum dot structures
    E. F. Pecora, W. Zhang, L. Zhou, D. J. Smith, J. Yin, R. Paiella, L. Dal Negro, T. D. Moustakas
    Bulletin of the American Physical Society, vol. 57
  • Room temperature low threshold stimulated emission of electron beam-pumped AlGaN-based deep UV laser structures emitting below 250 nm
    A. Nikiforov, W. Zhang, J. Woodward, J. Yin, E. Pecora, L. Zhou, L. Dal Negro, R. Paiella, D. Smith, T. Moustakas, A. Moldawer
    Bulletin of the American Physical Society, vol. 57

Conference participation

  • APS March Meeting 2013 – Baltimore, MD (USA) March 18 – 22, 2013 Poster presentation, Session V1
  • APS March Meeting 2013 – Baltimore, MD (USA) March 18 – 22, 2013 Poster presentation, Session V1
  • APS March Meeting 2013 – Baltimore, MD (USA) March 18 – 22, 2013 Oral presentation, Session C23
  • MRS Fall Meeting 2012 – Boston, MA (USA) November 25 – 30, 2012 Oral presentation, Symposium DD
  • MRS Fall Meeting 2012 – Boston, MA (USA) November 25 – 30, 2012 Oral presentation, Symposium DD
  • MRS Fall Meeting 2012 – Boston, MA (USA) November 25 – 30, 2012 Poster presentation, Symposium Z
  • CLEO Conference 2012 – San Jose, CA (USA) May 6 – 11, 2012 Oral presentation, Session “Low-dimensional Photonic Structures”
  • APS March Meeting 2012 – Boston, MA (USA) February 27 – March 2, 2012 Oral presentation, Session L28

Leadership experience

  • Laboratory Safety Coordinator for the Boston University Research Compliance – Environmental Health & Safety (2011 – 2013)

Teaching activity

  • Substitute lecturer for the EC471 class (Physics of Semiconductor Devices) at Boston University, Spring 2012 semester